Transmission 101

Transmission 101

Your vehicle is composed of thousands of parts. One of the most complicated of those systems is the transmission, itself composed of hundreds of pieces. This article could be pages long, going into detail about compound planetary gear ratios, vacuum modulators and torque converters, but this will provide a basic understanding of transmission function and trouble shooting. We have provided links below for those who would like to learn more about this amazing system.

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Looks complicated doesn’t it?


Basic Function

The transmission can refer to many different components that are used in the transfer of power from the engine to the wheels. For this article however, we will focus on the gearbox. Your vehicle’s engine RPMs are much faster than your wheels. Also, your vehicle generally needs more torque at lower speeds and more power at higher speeds. Though this is a complicated process, put simply, in an automatic this power is transferred from engine to transmission via the torque converter, while in a manual transmission it is transferred via the clutch. Most of the transmission and its working parts are encased in what is referred to as a transmission bell housing.

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Simple example of a transmission shifting system


Troubleshooting your transmission

Once again, this could get terribly complicated, but we’re going to go over the basic checks that you can do at your home or on a level surface to see what’s going on with your transmission.

  1. Check your fluid
    • Start your engine and place it in neutral (with the parking brake on) or Park if you have to.
    • Pop your hood and find your transmission dipstick. It could be labeled but if it is not, pull them out and check the fluid color. Transmission fluid is red.
    • Clean the dipstick then try again, the level of the fluid should be between the indicator marks.
    • The fluid should not be too dark red and it should not smell burnt.
  2.                    Check for leaks
    • Place a piece of cardboard underneath the transmission housing while your vehicle is parked. If it’s a really small leak, you might have to do this for a couple of days.
    • Look for spots on the cardboard. The transmission fluid will stain red.
  3.                    Be very mindful of what problems you are having with your transmission
    • Sometimes it can be difficult to reproduce the transmission issue in a test ride, so the technicians need to know the symptoms
    • Is the transmission slipping? When you you feel it shift into another gear, does is “slip” back into the previous gear?
    • Is there a delay?  When you are between gears, is an elongated pause?
    • Noises or feelings? Is there grinding or shaking coming from the transmission?


All of these will help tips will help you diagnose whether or not you should have a trained technician take a look at it. Many times, transmissions are neglected and owners forgo basic maintenance. Think of when the last time you had a transmission flush? When was the last time you changed your transmission filter?  For information regarding transmission service, repair, replacement or rebuild in San Antonio, Texas, please visit the following link

Bring Your Own Parts Transmission Service



Here are some additional links for the gear heads 🙂

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